Research On The Ultrasonic Measurement Technology Of Bolt Tension Based On The Sono-elasticity Principle

To guarantee the reliability and security of the steel construction, the clamp load of the joint bolt should be under strict control, sometimes even the tension of the bolt should be measured on-line. Referring to the sonic-elasticity principles, a indirect method is proposed for bolt tension measurement, based on the relation between the axial tension of high strength bolt and the time difference for the echo to return from the opposite end before and after the bolt is tightened. This method also takes the material factors and the clamp length into account. The method achieves high accuracy measurement by removing the measuring error caused by the discreteness of the thickness of the couplant and change in temperature. Based on the method, a new way on forecasting and revising the material factors is brought forward. The accuracy in bolt tension measurement is proved to be better than five percent, and thus is acceptable in most of the industry use.The thesis lucubrated the principle of ultrasonic bolt tension measurement and design of ultrasonic bolt tension measurement instrument. Emphasis on the sonic-elasticity principles, several key techniques were pertinently researched such as the ultrasonic send and incept technique and accurate sonic time measurement technique and coupling and so on.The thesis includes ten chapters.Chapter 1 is a survey. It summarizes present measurement for the tension of the high strength bolt, illuminates the principle of sono-elasticity and brings forward the ultrasonic bolt stress measurement based on the principle of sono-elasticity. It also summarizes the correlative ultrasonic basic theory and the application of the ultrasonic technique in the field of the stress measurement.Chapter 2 is the general deduction of the axial tension measurement technique based on sono-elasticity, which mainly includes mathematics expression of the principles of sono-elasticity, material factors definition, the calculate method of the mechanical elongation quantity, the effective clamp length of the bolt and the...